Currently there are a number of over-the-counter (OTC) preparations marketed for relief of “minor” muscular aches and pains. None of these agents appears to be effective for moderate-to-severe chronic pain. In fact, it appears that the only topical prescription analgesic specifically marketed for chronic pain is the LIDODERM® Patch which has been available by prescription since the late-1990s.
Notwithstanding the paucity of topical prescription agents currently available for treatment of moderate-to-severe pain (acute, post traumatic, and chronic), a number of factors make utilization of such preparations attractive and advantageous.
In particular, it would be desirable to have available for the relief of moderate-to-severe pain, an analgesic preparation which may be applied directly to the locus of pain and/or proximate the spinal column for nerves involved in the particular pain under treatment.
It would further be desirable for this preparation to avoid the systemic effects of analgesic and adjuvant agents, by relieving moderate-to-severe pain while reducing or eliminating systemic analgesics, e.g., non-steroidal anti-inflammatory drugs (NSAIDs) and/or opiates.
It would further be desirable to provide local anesthetic neural blockade over a sustained and ongoing period without associated appliances (e.g. indwelling catheters) and/or without motor or sympathetic nerve blockade.
It would further be desirable to relieve moderate-to-severe pain with a reduced dosage frequency.
Finally, it would be desirable more generally to provide topical preparations and generalized methods which allow therapeutic agents to be delivered by topical application to a patient's skin, such that after penetrating the skin, dispersion of the therapeutic agent is retarded, and prolonged localized effect is thereby achieved.
Currently, there do not appear to exist products which can achieve these desirable results, and do so with a satisfactory degree of safety and reliability.